Methodology for analysis of stress level based on asymmetry patterns of alpha rhythms in EEG signals

Stress can affect all people, regardless of age, gender or ethnicity. The human body uses stress as an adaptive response against several situations, but it can cause physical, mental or emotional distress. In stress situation the nervous system evokes the same physiological responses, whatever the type of stress and these responses cause changes in the physical, cognitive, emotional and social performance. This paper proposes to develop a methodology for analyzing the stress level using electroencephalographic signals (EEG) based on asymmetry patterns of alpha waves. The subjects of this research are professionals from Vitoria's Fire Department. Activities of the Central Nervous System are capture using Emotiv Epoc Headset, placed on the volunteer's scalp. The signals are analyzed from the frontal cortex at positions Fp1 (AF3), Fp2 (AF4), F3 and F4, according to of the international 10–20 system. The results are analyzed together with some peripheral physiological signals, such as: heart beat rate (ECG), peripheral blood flow, skin conductance, breath rate, body temperature and change in level of salivary cortisone. In addition, a psychological assessment of voluntary's stress is performed through a questionnaire of LIPP-ISS (Inventory of Symptom Stress). A validation study is conducted through a comparison with data available in literature, as well as with evaluation conducted by a psychologist. The results are analyzed in order to get a correlation between EEG signals and physical, mental or emotional stress.